A secondary battery is used as a substitute for a primary battery. In addition, the secondary battery is in widespread use as a power source for an electronic device such as a mobile phone and an IT device. Especially, the nonaqueous electrolyte secondary cell typified by a lithium ion battery has a high energy density. Accordingly, application of the nonaqueous electrolyte secondary cell is being developed for a large industrial electrical machine such as an electric vehicle.
FIG. 12 is an exploded perspective view illustrating a schematic configuration of a related nonaqueous electrolyte secondary cell. This type of nonaqueous electrolyte secondary cell is described in, for example, JP-A-2010-097822. The nonaqueous electrolyte secondary cell 100 includes an exterior in a hexahedron shape. This exterior is constituted of a container main body 110 and a plate-shaped cover portion 120. The container main body 110 has a box shape with an opening. The opening of the container main body 110 is sealed by the cover portion 120. The material of the cover portion 120 is aluminum.
The cover portion 120 has an opening as a through-hole 120a for extracting a terminal. On an upper side of the through-hole 120a, an insulation sealing material 122 is positioned. The insulation sealing material 122 has an outline in a shape of an octagonal prism. The insulation sealing material 122 is a component made of insulating material. The insulation sealing material 122 includes a bottom surface 122b surrounded by the framing body 122a. On the bottom surface 122b, a through-hole 122c is formed. The through-hole 122c extends to the through-hole 120a of the cover portion 120. That is, the through-hole 122c communicates with through-hole 120a. 
A connecting member 123 is a component made of conductive metal. At the center of the connecting member 123, a main body part 123a in a shape of an octagonal prism is positioned. Respective tubular portions 123b and 123c protrude from both surfaces of the main body part 123a. The main body part 123a fits the framing body 122a of the insulation sealing material 122. The tubular portion 123b is inserted into the through-hole 120a of the cover portion 120. This connects the tubular portion 123b to a current collector (not shown) housed inside of the container main body 110. The current collector is connected to a power generating element inside of the container main body 110.
A convex part 120b is formed on both ends of the cover portion 120 and at the outer side with respect to the through-hole 120a. The convex part 120b is a protrusion of the cover portion 120. The convex part 120b has a rectangular planar shape. Additionally, the convex part 120b is covered with a retainer 121, which is secured. The retainer 121 has a low-profile quadrangular prism shape. The retainer 121 is a component made of synthetic resin. The retainer 121 includes a backside surface (not shown) with a depression corresponding to the shape of the convex part 120b. Accordingly, the retainer 121 is secured on the cover portion 120 by fitting to the convex part 120b. 
Additionally, a terminal member 125 is positioned on an upper side of the retainer 121. The terminal member 125 electrically connects the nonaqueous electrolyte secondary cell 100 to an external load or another battery. The terminal member 125 is a component made of high-strength conductive metal such as iron and stainless steel. The terminal member 125 includes a bolt portion 125a and a base portion 125b. The bolt portion 125a includes a surface with a thread. The base portion 125b is formed at a root portion of the bolt portion 125a. The base portion 125b has an outline in a quadrangular prism shape.
On a principal surface of the base portion 125b at a side facing the cover portion 120, a depressed part 125c is formed. The depressed part 125c has a shape corresponding to the shape of the retainer 121. The depressed part 125c fits the retainer 121. Accordingly, the terminal member 125 is secured to the cover portion 120 in a state insulated from the cover portion 120.
Additionally, a bridge member 124 is placed to cover both the connecting member 123 and the terminal member 125. The bridge member 124 includes a surface on which a through-hole 124a and a through-hole 124b are formed. The bridge member 124 is a plate-shaped component made of conductive metal. The tubular portion 123c of the connecting member 123 is inserted into the through-hole 124a. The bolt portion 125a of the terminal member 125 is inserted into the through-hole 124b. In this state, a distal end of the tubular portion 123c is swaged. Accordingly, the bridge member 124 is secured to the connecting member 123. This electrically connects the connecting member 123 and the terminal member 125 together.
In this nonaqueous electrolyte secondary cell 100, electricity stored inside of the container main body 110 is available through the terminal member 125. Specifically, wiring (not shown) of the external load is mounted on the bolt portion 125a of the terminal member 125, and fastened by a nut and similar member. This electrically connects the nonaqueous electrolyte secondary cell 100 and the external load together.
In the nonaqueous electrolyte secondary cell 100 as described above, the terminal member 125 is secured to the cover portion 120 via the insulative retainer 121 as illustrated in FIG. 12. In this case, rattling may occur between the retainer 121 made of insulative resin material and the convex part 120b of the cover portion 120 made of metallic material. Accordingly, in this technique, it is difficult to stably secure the terminal member 125 to the cover portion 120.
In an electric storage device like the nonaqueous electrolyte secondary cell 100, a conductive path that extends to the outside of the housing container from the power generating element connects to a connecting terminal like the terminal member 125 in a state insulated from the housing container by an insulation structure like the retainer 121. However, there has been a problem that it is difficult to stably secure this insulation structure to the housing container.